Thomas
E. RocheUniversity Distinguished Professor
Structure, function and regulation of mammalian pyruvate dehydrogenase complex.
B.S. 1966, Regis College
Ph.D. 1970, Washington State University
Phone: 785-532-6116
Fax: 785-532-7278
Email: bchter@ksu.edu
Office: 101A Burt Hall
In a full context of the structure, function, and interactions of the components of the pyruvate dehydrogenase complex (PDC), our research seeks to elucidate the short-term regulation of the mammalian PDC. The primary target is understanding the structure, molecular interactions and effector control of the pyruvate dehydrogenase kinase (PDK) and pyruvate dehydrogenase phosphatase (PDP) isoforms. PDKs phosphorylate and inactivates the E1 (pyruvate dehydrogenase) component and PDPs dephosphorylate and reactivate E1. Differences in the operation and the effector responsiveness of the kinase and phosphatase isoforms are dependent upon differences in the functional interplay of the 4 PDK isoforms and 2 PDP isoforms with the dihydrolipoyl acetyltransferase (E2) component and E3-binding protein (E3BP). To alter kinase and phosphatase function and regulation, E2 serves as an anchoring scaffold, as an adaptor protein directly aiding efficient phosphorylation and dephosphorylation, as a processing unit in translating effector signals, and as a direct allosteric agent in consequentially altering regulatory enzyme activities. We have uncovered these roles, as well as an adaptor role of E3BP in the case of one PDK isoform, and seek to learn the molecular basis by which these occur. Our efforts are aided by advances that we have made in developing E. coli expression systems for making most components (E1, E2, E2-E3BP, E3, 4 PDKs, catalytic subunit of PDP1) and a large number of E2 constructs. We use a combination of standard enzymology, molecular biology, and biophysical techniques.
Selected Publications
Hiromasa and T.E. Roche (2003) Facilitated Interaction between the Pyruvate Dehydrogenase Kinase Isoform 2 and the Dihydrolipoyl Acetyltransferase, J. Biol. Chem. 278, 33681-33689.
J.A. Morell, J. Orme, R.J. Butlin, T.E. Roche, R.M. Mayers, and E. Kilgour (2003) AZD7545 is a selective inhibitor of pyruvate dehydrogenase kinase 2, Biochem. Soc. Trans. 31, 1168-1170.
Y. Hiromasa, T. Fujisawa, Y. Aso, and T.E. Roche (2004) Organization of the Cores of the Mammalian Pyruvate Dehydrogenase Complex Formed by E2 and E2 plus the E3-binding Protein and their Capacities to Bind the E1 and E3 Components, J. Biol. Chem. 279, 6921-6933.
H. Bao, S. A. Kasten, X. Yan, and T. E. Roche (2004) Pyruvate dehydrogenase kinase isoform 2 activity limited and further inhibited by slowing down the rate of dissociation of ADP, Biochemistry 43, 13,432-13,441.
H. Bao, S. A. Kasten, X. Yan, Y. Hiromasa, and T. E. Roche (2004) Pyruvate dehydrogenase kinase isoform 2 activity stimulated by speeding up the rate of dissociation of ADP, Biochemistry, Biochemistry 43, 13,442-13,451.
A. Turkan, Y. Hiromasa, and T. E. Roche (2004) Formation of a complex of the catalytic subunit of pyruvate dehydrogenase phosphatase isoform 1 (PDP1c) and L2 domain forms a Ca2+-binding site and captures PDP1c as a monomer, Biochemistry 43, 15073-15085.